Nonlinear Landau damping can occur in an ion beam-plasma System, where the space charge waves of the ion beam decay into the Trivelpiece-Gould modes by the nonlinear wave-particle interaction with beam or plasma ions. The nonlinear wave=particle coupling coefficients of two waves in these nonlinear interactions and the rate of ion heating due to nonlinear Landau damping by the interaction with plasma ions are studied by theoretical calculation.
Power absorption of the plasma in high-frequency discharge are investigated. As a result, two peaks of the absorbed power are observed with regard to gas pressure. One peak can be explained by the increase of positive conductance of the plasma. Another peak can be explained by the appearence of a negative conductance which causes by the interaction between radial electron diffusion velocity and axial high-frequency magnetic field. Moreover, the effects of external magnetic field and microwave incidence upon this negative conductance are investigated.
A step response of a plasma column to the desired plasma position is examined for several types of feedback control by solving the equation of motion of a plasma column in a resistive shell. Experimental results in JIPP T-II are also described.